I think it's pretty ludicrous that they're doing Spider-Man again so soon. I'm less concerned about being faithful to the source material than I was in 2002. We recently got a (more or less) faithful version of the character.
So why not cast a black guy if he's right for the part? Just do something different.
That's the problem - you'd only be doing it to "do something different".
If that's the best reason anyone can come up with then you may as well scrap the franchise now.